THE CLASS 1 BUSINESS

,f: * * THIS CLASS I BUSINESS

Sir, By an amazing coincidence, I have been attempting for some time past to design a 500-cc. single-cylinder racing car, to be built after the war, and Kenneth Neve’s article in your August issue covers all the things I have been thinking. You ask what the performance of such a car would be, and I have enough data to work this out fairly accurately. As Mr. Neve says, the old side-valve 1,900-c.c. J. A.P. engine, with which my little car first appeared, did not give so much pow( r as a good modern 500. I would go further and say that the current type of dirt-track J.A.P. single gives almost as much power as my old o.h.v. twins. (Far be. it from me to belittle Mr. J.A.11.’s early twins, and I still think that when I bought the sidevalve in 1929 for £7 10s. Od. I got value for money 1) The crux of the whole thing is powerweight ratio, and the following table shows how quickly a given amount of b.h.p. has moved a certain eight up two well-known gradients. It should be noted that the 1).11.p. figures are the engine-maker’s, and my engines were rather above standard when raced, but not enough to worry about : Course Time .B.H.P. Weight Engine

Now the ” dirt “

J.A.P.

of 500 c.c.

gives about 42 b.h.p. with a 16 to 1 compression ratio and also a wonderful poke right down to almost zero revs. I believe the latest racing Norton gives considerably more power than this, but has no urge below 4,000 r.p.m. Anyway, if we put our 49 b.h.p. ” 500 ” into a really good chassis, and the car ready for racing weighs about 4 cwt., we should, by virtue of modern suspension systems, be able to stick on the road a great deal better than poor old ” Mary,” and climb Lewes in 21 sees. and Shelsley in 44 sees.

Although these times may sound creditable for so small a car, it should be remembered that these figures have been approached by sports cars, such as Mr. Lycett’s 8-litre Bentley and Mr. Follett’s Special Railton, and it might seem silly to run a class for racing cars which are no faster than a good swats car. I am, Yours etc.,

J. V. BOLSTER.

Wrotham, Kent.